Tiglic aldehyde is an important raw material for the synthesis of isoterpenes. Tiglic acid ##STR2## which is obtained by oxidation of tiglic aldehyde is useful as a raw material for the synthesis of driers for perfumes, varnishes, inks, and the like. Further, a chloride of tiglic aldehyde [4-chloro-2-methyl-2-butene-1-al, ##STR3## ] is a useful compound to extend an isoterpene chain at one.
Hitherto, as a method for the production of tiglic aldehyde, a so-called Cross's aldol condensation method wherein acetaldehyde and propionaldehyde are condensed in a strong basic condition is known. However, this method has a drawback that the yield of said aldehyde is poor with a large quantity of various by-products being formed (see M. B. Green, W. T. Hickinbottom, Journal of Chemical Society, page 3262 (1975)).
With the purpose of producing tiglic aldehyde in a good yield from materials which are available at a low price, the present inventors have extensively investigated various synthesis routes thereof and achieved this invention.